private void OnFreeContext(object sender, DisconnectedEventArgs e)
        {
            var imp = (HttpClientContext) sender;
            imp.Cleanup ();

            if (!imp.EndWhenDone)
            {
                imp.Available = true;
                lock (_contextQueue)
                    _contextQueue.Enqueue(imp);
            }
            else
            {
                imp.Close ();
                imp.Available = false;
            }
        }
 private void OnFreeContext(object sender, DisconnectedEventArgs e)
 {
     var imp = (HttpClientContextImp) sender;
     imp.Cleanup();
     lock (_contextQueue)
         _contextQueue.Enqueue(imp);
 }